[Ada] Compiler abort on a dynamic predicate used in a precondition

[Ada] Compiler abort on a dynamic predicate used in a precondition

This patch suppresses the generation of a predicate check when the
expression is a formal IN parameter of a subprogram S. If the check is
being applied to the actual in a call, the call is either in the body of
S, or in an aspect specfication for S, e.g. a precondition, In both
cases the check is redundant bevause it will be applied on any call to
S. In the second case the expansion of the predicate check may lead to
out-of-scope references the the formal.

2019-07-05  Ed Schonberg  <schonberg@adacore.com>

gcc/ada/

	* checks.adb (Apply_Predicate_Check): Except within the
	subprogram body that defines the formal, do not apply predicate
	check on a formal IN parameter: such a check is redundant and
	its expansion can lead to out-of-scope references when it is
	originates in a function call in a precondition,

gcc/testsuite/

	* gnat.dg/predicate7.adb, gnat.dg/predicate7.ads,
	gnat.dg/predicate7_pkg.ads: New testcase.

From-SVN: r273106